Near-Misses and their Uses

byPaul GilsteronFebruary 18, 2013

We can hope that the celestial events of February 15, including the spectacular fireball over Chelyabinsk and the near-miss from asteroid 2012 DA14, have raised public consciousness about Earth’s neighbors in space. And indeed, this seems to be the case. Media outlets were flooded with articles, photos and video, and talk show hosts found themselves asking what could be done to prevent future impacts. Could all of this prompt a new surge of interest in space?

The scenario is exactly what Arthur C. Clarke wrote about in Rendezvous with Rama (1972), where what it takes for humanity to get serious about developing a protective system (and, by extension, about pushing its space program forward) is an impact. We can be grateful that the one we’ve just seen was far smaller than Clarke’s, as described in the first chapter of the novel:

At 0946 GMT on the morning of September 11 in the exceptionally beautiful summer of the year 2077, most of the inhabitants of Europe saw a dazzling fireball appear in the eastern sky. Within seconds it was brighter than the Sun, and as it moved across the heavens — at first in utter silence — it left behind it a churning column of dust and smoke.

Somewhere above Austria it began to disintegrate, producing a series of concussions so violent that more than a million people had their hearing permanently damaged. They were the lucky ones.

Clarke goes on to recount the impact in northern Italy, where Padua, Verona and Venice are destroyed by the combination of impact and tsunami. The deaths of 600,000 people and the great chunk torn out of human history create a resolution that this must not happen again, and out of this is born the system of radars that eventually finds the alien intruder dubbed Rama. Clarke’s book is about the encounter with this enigmatic vessel, but the asteroid-warning radars he imagines create the kind of warning grid we may eventually put in place.

The B612 Foundation has been making the case for asteroid detection and mitigation studies for some years now. Its Sentinel Space Telescope is scheduled for launch in 2018, with the aim of detecting over 90 percent of asteroids over 100 meters in diameter — these are the ones large enough to destroy an entire region of the planet if they were to hit us. Sentinel also aims to track more than 50 percent of near-Earth asteroids in the DA-14 category. With decades of warning, says CEO Ed Lu in this B612 news release, we can use existing technology to destroy or alter the trajectory of any such objects.

Chelyabinsk and 2012 DA14 also put the University of Hawaii at Manoa’s work on ATLAS into the news. The Asteroid Terrestrial-Impact Last Alert System — an ominous title, that — is to operate eight telescopes, each with a camera of up to 100 megapixels, on sites in the Hawaiian Islands. The goal here is to offer, according to this news release from the university’s Institute for Astronomy in Honolulu, a one-week warning for a 45-meter asteroid and a three-week warning for a 140-meter object. That’s enough time, according to astronomer John Tonry, “to evacuate the area of people, take measures to protect buildings and other infrastructure, and be alert to a tsunami danger generated by ocean impacts.”

But among the spate of asteroid warning news items that surged over the weekend, the project that caught my eye first was one called DE-STAR, the explanation of whose acronym is so tortuous that I will direct you to the University of California at Santa Barbara news release it appeared in. What UC-Santa Barbara researchers Philip Lubin and Gary Hughes are proposing is a system that could, over the course of a year, destroy asteroids ten times larger than 2012 DA14, using a massive phased array of lasers to break up or evaporate the object.

Says Hughes:

“This system is not some far-out idea from Star Trek. All the components of this system pretty much exist today. Maybe not quite at the scale that we’d need –– scaling up would be the challenge –– but the basic elements are all there and ready to go. We just need to put them into a larger system to be effective, and once the system is there, it can do so many things.”

DE-STAR is being described as a ‘directed energy orbital defense system,’ one that uses solar energy to feed its lasers. The researchers have calculated DE-STAR systems in various configurations, including a 100-meter DE-STAR 2 and a 10-kilometer DE-STAR 4, the latter capable of delivering the energy needed to obliterate a 500-meter asteroid in about a year.

Image: Concept drawing of the DE-STAR system engaging both an asteroid for evaporation or composition analysis, and simultaneously propelling an interplanetary spacecraft. Courtesy Philip M. Lubin.

And now we start getting into Bob Forward territory as Lubin and Hughes go on to describe a DE-STAR 6 that would function not only in asteroid defense but as the propulsion system of an interstellar spacecraft, beaming enough laser energy to the craft to get it up to a substantial percentage of the speed of light. An asteroid mitigation strategy that involved planetary safety, power generation and spacecraft propulsion is a tempting long-term goal, but a DE-STAR 2 about the size of the International Space Station could begin small-scale trajectory alterations on a variety of objects as we experiment with planet-defending techniques.

Meanwhile, many of us talked to Claudio Maccone at the Huntsville conference and learned of his plans to attend the IAA’s Planetary Defense Conference, coming up in Flagstaff on April 15-19. Claudio crosses the ocean all the time, as inveterate a conference-goer as I’ve ever seen, but who would have thought this year’s Planetary Defense meeting would become so highly visible? You can bet media coverage at Flagstaff will be considerably higher than in years past thanks to Chelyabinsk and 2012 DA14, making them unusually effective wake-up calls for our species.

Comments on this entry are closed.

Jim EarlyFebruary 18, 2013, 11:12

Everyone talks about asteroids, and there is almost no discussion about comet collisions. In 1994 Shoemaker-Levy 9 demonstrated the scope of a comet impact with Jupiter. I’m sure the comet impact rate is much lower, but does anyone have the actual comparison numbers?
There are several asteroid detection projects which is the appropriate response for the near term. Are we ignoring the comet problem because there is no answer or because the probablilities are so low?

That this meteor hit Russia may be especially fortunate. This event may change their modest space plans. Putin may decide to allocate more investment into Russia’s space capabilties. To defend Russia against meteors afterall. If the meteor hit Chad it would have been no big political impact.
Now we need another one to break the windows in my town, Ottawa.

There was another relatively large meteor over Florida this weekend. Although I do not hold out hope that something like these ‘close shaves’ will motivate us to put more emphasis on space based technologies, being an eternal optimist I certainly hope it will.

I’m not sure why they’re talking about obliterating or evaporating or vaporising an entire asteroid when vaporising a small part of it would presumably apply sufficient thrust to nudge it away from a collision path. In addition, the attempt at complete vaporisation would increase the danger of its uncontrolled breaking up into a number of large and still threatening fragments. Better to keep as much as possible intact. These are in any case valuable properties by virtue of their composition and proximity to Earth; in my view any planetary protection programme should work hand in hand with an asteroid industrialisation one.

Also the head of Russian Astrology Institude, Lidiya Ryhlova, said they need €1,4bn over 10 years for the Complex Asteroid Threat Program in Russia and submit the proposal for the Deputy prime minister. It’s just to set up the program and get it run. They will need another $500mln for upgrading the suitable telescopes and make them fully-automated to trace the NEOs. (http://lenta.ru/news/2013/02/18/meteor/)

I saw today a short clip of a press conference where Russian renowned astrologist told to the journalist that there is need for 10 wide-field
(4-6 arc sec (?)) telescope over the World to cover the whole sky. They would give capability for predicting NEOs at 1 mln and 5 mln kilometers.

It seems to me that all residents of that lucky Russian city should be thanking their lucky stars. I have read calculations of the explosive yield produced from the explosion of that small asteroid as high as 300 kilotons.
If trajectory and/or composition had been a little different and the meteor had exploded a kilometer or so directly above downtown, well, the name Chelyabinsk would have acquired great historical status.

Unlike the Arthur C. Clarke novel where it took an actual impact to motivate governments I would hope this kind of scare will motivate increased funding being directed at improving our capability at detecting and mitigating impact threats. We really have to stop trusting to luck.

And besides, any increase in astronomical abilities always brings an improvement in our understanding of the Universe. Even if it’s just our little corner of it.

In 2010 John Holdren , the White House Science Advisor, had solicited Congress to make a national priority for space funding of asteroid detection and deflection [Link to Holdren’s Letter to Congress:
[http://www.whitehouse.gov/sites/default/files/microsites/ostp/ostp-letter-neos-house.pdf]. After weeding through the politics of space project funding he is evaluating a $2.6 billion plan as part of the space exploration agenda for the next decade. Current telescopes estimate large asteroid events will occur every Millennia [http://www.popsci.com/science/article/2013-02/how-powerful-new-telescopes-are-helping-us-find-more-asteroids-hopefully-just-time] so DESTAR-6 would become obsolete between events.

This was a good wake up call, but interest will fade quickly outside the affected area. Hopefully those in charge of funding will take advantage of the uptick before all is forgotten. It’s a small window, maybe just a few weeks, so they need to hurry, or the next ‘wake up call’ could be more like what Clarke described.

Detection is not deflection; we can create a warning system but if we do not build an interceptor to go with it then what is the point? A comet coming from behind the sun might only give us a month or so of warning. In that case the several hundred megatons of H-bombs necessary to deflect it would not be ready in time.

339 billion for the F-35 Stealth Fighter- actually a trillion over the life of the program- but we have an ex-astronaut (Ed Lu) going begging for a few million for a single warning satellite.

What will it take? Everyone has now been advised that it only happens once every thousand years or some other worthless figure to make them forget about it.
We could get hit by two dinosaur killers tomorrow and on the scale of geologic time it would be just a blip on that convenient probability curve.
I am fairly unhappy about the lack of a response by the U.S.
We are probably going to go extint.

There is another consideration, which is avoiding a global catastrophe of our own making. Imagine if this even would have happened ( over a Soviet weapons site no less!) during the cuban missle crisis. Half the planet would be wearing lead lined Jock straps my now. Even now, a meteor strike in the middle east or parts of Asia might be misread as a nuclear attack. With early warnings of a space object impact. We could avoid the miscalculations and possible deployment of retaliatory nuclear strikes against perceived enemies. By the way… asteroid mining might be weaponized in the wrong hands. ( this was explored as a cultural possibility in the excellent novel “shockwave rider” along with personal computers, the internet, internet virus, the rise of the hacker culture and a host of other parts of our lives we take for granted) hats off to John Brunner!

The ability to patrol & defend our planet from ‘dangerous impact events’ sounds crazy to a lot of people. But this enterprise is the ‘moral equivalent’ of war. We finally have a use for our knowledge that was traditionally reserved for the current stockpiles of nuclear weapons.
The gentle nudging of space rocks in interplanetary flight is great… but you really need a backup just in case of initial operational failure or time and passive handling is insufficient for a given case of an event.
Building a ‘planet-buster’ makes more sense than having 17,000 ICBMs pointing towards ourselves?
In reality, could the nations of this Earth cooperate on this issue?
Could we need more than one system? Before this recent event at Chelyabinsk, the Russians have stated that they would go it alone if necessary.
Asteroid defense policies should have been seriously discussed since Shoemaker-Levy happened back in 1994!
Beyond the geopolitics, making space hardware and support systems to manage this problem should have no serious obstacles. Our people in this time have the skills to deal with this preventable tragedy.

I remember reading Rendezvous with Rama some years ago – it’s a classic of hard sci-fi. I always found it strange that the date of the fictional disaster was September 11. Anyway…

I agree that nudging asteroids would be the most efficient solution. Hopefully the Chelyabinsk warning shot will be enough to motivate the scaling-up and organization required for a system of asteroid warning/prevention. A real-world Spaceguard is definitely within reach.

Of course, the long-term solution to this and other dangers is space colonization, which will do much to ensure our survival in this Universe.

With respect, we’ve known about another type of impending “collision” for some decades and have done zero to mitigate the cause and consequence of man-made global WARMING. If B612 is successful and provides early warning why would anyone expect a reaction other than denial and indifference?

which is the biggest threat? Asteroids, comets, CO2, overpopulation…ignorance? Got it in 5.

Лидия Рыхлова / Lidiya Ryhlova – she is a head of Astrometry / Отдел космической астрометрии.

Turns out Russians have Planetary Defence Association too, but it’s more like a dormant club and personal initiative of the founders. Non the less they have a substantial memeber list. There are some articles about deflecting or destroying dangerously close NEOs but I guess things has changed since 2003 and the basic discussion is about flying satellites into or around the NEO. Slightly about deflecting it w/ sidekick mirrors orbiting closely the NEO approaching satellite. Didn’t find the need to link the article in Russian.

I’m not sure I’m buying into this laser system as the best solution for mitigating asteroid collisions. There are so many other, quite elegant solutions available.

The DoD seems the obvious institution to work on this. However, I also think that this is an opportunity for companies like Planetary Resources to test ideas on deflection with some public monies, rather than wait interminably for a government run test program. They may be able to get the ball rolling relatively quickly, so that we have a chance of getting some hardware in place for asteroids with known trajectories.

The problem is what to do with those objects that appear quickly with little time to prepare. Is it possible to deploy detectors to prevent these surprises? If not, what is the solution for asteroids and comets that give little warning, given we know that nuclear bombs won’t work on rubble asteroids?

Adviser to Russian deputy prime minister claimed that other country astronomers have calculated the cost of NEO sentinel program and this insane sum of money – $28bn & more – plus nobody knows what they’ll get.

The deputy prime minister, Ragozin, he oversees defence budget, wasn’t very thrilled about the proposal. Although he in March 2012 made the surprising announcement that it’s time to step up the planetary defence program againts NEOs.

Astro Channel asked Rogozin over Twitter what the 58bn rubles ($1.4bn) include on which he quite bluntly answered “58 bn green for figthing the aliens – chicks in the club told me. The other chicks on the twitter yelling – theft!”.

The joke is that Abramovich paid for Chelsea football club $1,5bn. In this terms the asked funding is just peanuts.

The arguments Rogozin using that noone (especially USA and Russia) has this capability and no need to exaggerate the importance of the system. He’s more into international cooperation on this matter but this argument is more like pretext.

No sudden changes in the policies or budget priorities despite whatever one has recently told to the press.

Skyfall: will a Russian meteor and an asteroid flyby change our minds about the NEO threat?

On Friday a meteor disintegrated in the skies of souther Russia, causing considerable damage to buildings in the city of Chelyabinsk. Jeff Foust examines whether that, and an asteroid flying close by the Earth the same day, will raise awareness enough about the threat posed by near Earth objects to generate increased government or private funding for search efforts.

“339 billion for the F-35 Stealth Fighter- actually a trillion over the life of the program- but we have an ex-astronaut (Ed Lu) going begging for a few million for a single warning satellite.

“What will it take? Everyone has now been advised that it only happens once every thousand years or some other worthless figure to make them forget about it.

“We could get hit by two dinosaur killers tomorrow and on the scale of geologic time it would be just a blip on that convenient probability curve.
I am fairly unhappy about the lack of a response by the U.S.
We are probably going to go extint.”

When astronomers (which ones, BTW?) said that a space rock the size of the one that hit Russia last Friday happens about once a century, when and what were they basing this on? Has there been new research data to revise this time frame?

Fate has a funny way of proving human predictions wrong (aka, the unsinkable Titanic). Too bad science education and scientists have not done their full part to get across the fact that we live in a Universe where there are lots of space rocks and iceballs flying around, many of which can hit Earth at any given moment without warning.

This is also why the DoD has a $700 billion ANNUAL budget and NASA gets $18 billion annually, with cuts threatened all the time. Republicans or Democrats in the White House, it does not seem to matter when it comes to our space agency. NASA is always easy pickings because the masses think what it does has little relevance to their daily lives.

It always seems to take a Pearl Harbor or 9/11 before people wake up to the issues at hand, if ever. Perhaps more effort to make humanity aware that we are on but a pale blue dot in a vast cosmic sea is required. Do not leave the job to Hollywood and our public education system.

@Skotch Vail: you’re right, breaking up a larger asteroid into smaller pieces is almost always a good thing (contrary to what one Very Bad Astronomer seems to have popularized). An example: the Chelyabinsk object was approximately 15 meters in diameter while 2012 DA14 is approx. 45 meters. So, DA14 has about 27 times the volume and mass (assuming similar density for the mass estimate, which actually isn’t known). Would you rather get hit by 27 different Chelyabinsk objects separated in time and space and almost all giving airbursts or one DA14 which causes a Tungunska like event (or Meteor Crater in AZ if it’s iron-nickel). Not a hard choice to make! Of course, if you do the break-up even a few months in advance and impart a modest delta-V to the fragments, most of them will actually miss the earth anyway.

ESA is stepping up it’s commitment on NEO sentinel programm and on May 22nd opening its organization.

———-
Time for Europe to beef up asteroid vigilance: ESA
Agence France-Presse February 21, 2013 11:01
Europe must strengthen its watch for dangerous space rocks, the head of the European Space Agency’s asteroid surveillance programme said Thursday, a week after a meteor struck Russia in a blinding fireball. Nicolas Bobrinsky, in charge of ESA’s four-year-old Space Situational Awareness (SSA) programme, said his unit would inaugurate a centre in Rome on May 22 to coordinate observatories’ sightings of passing asteroids. The SSA is also working on a prototype “fly’s eye” telescope, with specially-designed wide vision, to help surveillance of the cosmos, he said
—–http://www.gizmag.com/esa-russian-meteor/26310/

n an interview with Nicolas Bobrinsky, Detlef Koschny – who is responsible for ESA’s Space Situational Awareness (SSA) program’s Near-Earth Object operations – outlined some of the findings and their importance in detecting similar meteors before they hit.

ESA’s main concern is with the 600,000 known asteroids in our Solar System and particularly the 9,000 that pass close to the Earth. The agency is working with NASA and European national space agencies to develop an early warning system to detect similar meteors in the future.

Koschny described a 2008 meteor that was detected by accident 20 hours before it hit in the Sudan. If the Chelyabinsk meteor had enjoyed a similar heads up, people in the region would have had sufficient warning to prepare for the blast and stay clear of windows or weakened structures.

As part of its effort to provide such a warning, ESA’s SSA program is working to carry out an extensive sky survey using up to six automated 1-meter (39.4-in) telescopes to photograph the entire sky. By comparing images taken at various points and times, it would be possible to detect any new objects orbiting the Sun by their shifting in the images. From these shifts, the trajectory of the objects can be calculated and the threat, if any, they pose to Earth can be assessed. According to ESA, such a survey – along with space-based observations – would be able to detect an object the size of the Chelyabinsk meteor several days before impact.

I do not know which is worse- the internal threat of an engineered pathogen that leaves no survivors or the external threat of a comet or asteroid impact. Either one can do us in. The solution is a Moonbase from which to launch nuclear propelled spaceships on missions to establish self-sufficient colonies- or intercept impact threats. We have the money and the technology; we are just too stupid to understand we are an endangered species. Every day we waste is natural selection at work.

On Monday NEOSSat will be launched which goal will be mapp NEOs in less explored section of cosmos. They hope to find a more proper asteroid for NASA manned landing something w/ withd around 500 meters.

Ogleearth link was inspiration for the paper and oglearth entry showed how much a dedicated community can collect data and devise results by harnessing crowdsourcing power. Impressive what mathematical tools everyday user have in their reach and how w/ desktop and map application you can turn it into useful information.

I think this is another good example of need to involve hard-core, prosumer and serious POI into specific area of research. Compliments to very good extend “The Draco Kill Shot” article here. https://www.centauri-dreams.org/?p=26504

Yes, the sky is falling. The asteroid impact that took place in Chelyabinsk, Russia, on February 15, 2013, has jump-started an international conversation about planetary protection and whether or not there is a really big asteroid/meteor/comet out there with our name on it. There is, we just haven’t found it yet.

Miniscule objects enter the atmosphere all the time; occasionally larger objects come down—the Tunguska (1908) and Chelyabinsk (2013) events are prime examples of this—and once in a very great while a mass extinction impact takes place as in the Cretaceous–Paleogene extinction event of 66-65 million years ago that wiped out the dinosaurs.

“I first heard a scientist talk about this in 1992 when he explained that several thousand interplanetary objects were on collision courses with Earth, and that several small pieces entered the atmosphere every day. It is only a matter of time before a really large one hit the Earth, and the results could be catastrophic.

“The scientist urged the cataloging of all possible Earth-crossing asteroids, the tracking of their trajectories, and the beginning of research and development on countermeasures to deal with those objects heading for Earth.

“Most of the audience departed this speech with mixed feelings, recognizing the reality of what had been said and also denying that it bore any relationship to reality. Indeed, while the scientific theory that a great galactic meteor slamming into the Earth had created a form of “nuclear winter” that made the dinosaurs extinct was gaining currency at the time, few believed a real threat existed in the present.

“After all, at that time the United States had just achieved the most impressive triumph of its history, defeat of the Soviet Union in the Cold War and stood essentially omnipotent in the world as a superpower. Now another threat is before us: this time it’s from space and there is currently no technology to defeat it.”

Russians have confirmed inital estimations about the bolide – 10-18 000 ton, 17-20 meters in size, yield 500 kiloton, yield reached to Chelyabinsk was no more than 1 kiloton, around 10% of the bolide fell on ground as debris, debrise is scattered over 150 x 20 km area, in spring most of them will be located, biggest discovered lump so far is 1.8kg.

Russians agreed over a roundtable to form a World’s first Warning and Deflection Center of Cosmic Threats (центр по предупреждению и отражению космических угроз) in cooperation between MoD, Roskosmos, Rosatom, and Academy of Sciences. The goal of the center is catalog, improve and develop means of detection, design and test methods of deflection, including possible missions on Cosmic Objects of Interest. Rosatom already stated for deflecting celestial bodies bigger than 1 km requires nuclear ammunition more than 1Mt yield which requires specific development and test. In general Russians admit they assume 50% of Celestial Objects of Interest which pose imminent or real threat could be detected.

Also they clearly stated international help and cooperation is necessary and this secondary goal next to making the WDCCT run.

Precovery of near-Earth asteroids by a citizen-science project of the Spanish Virtual Observatory

This article describes a citizen-science project conducted by the Spanish Virtual Observatory (SVO) to improve the orbits of near-Earth asteroids (NEAs) using data from astronomical archives. The list of NEAs maintained at the Minor Planet Center (MPC) is checked daily to identify new objects or changes in the orbital parameters of already catalogued objects. Using NEODyS we compute the position and magnitude of these objects at the observing epochs of the 938 046 images comprising the Eigth Data Release of the Sloan Digitised Sky Survey (SDSS). If the object lies within the image boundaries and the magnitude is brighter than the limiting magnitude, then the associated image is visually inspected by the project’s collaborators (the citizens) to confirm or discard the presence of the NEA. If confirmed, accurate coordinates and, sometimes, magnitudes are submitted to the MPC. Using this methodology, 3,226 registered users have made during the first fifteen months of the project more than 167,000 measurements which have improved the orbital elements of 551 NEAs (6% of the total number of this type of asteroids). Even more remarkable is the fact that these results have been obtained at zero cost to telescope time as NEAs were serendipitously observed while the survey was being carried out. This demonstrates the enormous scientific potential hidden in astronomical archives. The great reception of the project as well as the results obtained makes it a valuable and reliable tool for improving the orbital parameters of near-Earth asteroids.

“Researchers at The Open University (OU) and The University of
Manchester have found conclusive proof that Ancient Egyptians used
meteorites to make symbolic accessories.

The evidence comes from strings of iron beads which were excavated in
1911 at the Gerzeh cemetery, a burial site approximately 70km south of
Cairo. Dating from 3350 to 3600BC, thousands of years before Egypt’s
Iron Age, the bead analysed was originally assumed to be from a
meteorite owing to its composition of nickel-rich iron. But this
hypothesis was challenged in the 1980s when academics proposed that
much of the early worldwide examples of iron use originally thought to
be of meteorite-origin were actually early smelting attempts.

Subsequently, the Gerzeh bead, still the earliest discovered use of
iron by the Egyptians, was loaned by the Manchester Museum to the OU
and the University of Manchester’s School of Materials for further
testing. Researchers used a combination of the OU’s electron
microscope and Manchester’s X-Ray CT scanner to demonstrate that the
nickel-rich chemical composition of the bead confirms its meteorite
origins.”

On the last day of May 2013 asteroid 1998 QE2 passed relatively closely by our planet, coming within 6 million kilometers… about 15 times the distance to the Moon. While there was never any chance of an impact by the 3 km-wide asteroid and its surprise 750 meter satellite, astronomers didn’t miss out on the chance to observe the visiting duo as they soared past as it was a prime opportunity to learn more about two unfamiliar members of the Solar System.

By bouncing radar waves off 1998 QE2 from the giant dish at the Arecibo Observatory in Puerto Rico, researchers were able to construct visible images of the asteroid and its ocean-liner-sized moon, as well as obtain spectrum data from NASA’s infrared telescope in Hawaii.

What they discovered was quite surprising: QE2 is nothing like any asteroid ever seen near Earth.

Who’s been taking potshots at Earth? A new study shows how a 200-metre-wide cluster of rocks, first spotted by scientists in 2011, could have spawned the Chelyabinsk meteor which exploded over Russia earlier this year. If correct, that means we may need to watch out for further impacts from other fragments of the cluster, which are still at large, in orbit around the sun. The meteor that exploded over Russia on 15 February, scattering debris across the Chelyabinsk region and injuring hundreds, came as a complete surprise. Since then researchers have traced it to the Apollo asteroid family, but no one had matched it to a particular member of the group.

Now Carlos de la Fuente Marcos and his brother Raul, both of the Complutense University of Madrid, Spain, are pointing the finger at asteroid 2011 EO40. Roughly 200 metres wide, it is a rock – or cluster of rocks – previously listed as potentially hazardous by the International Astronomical Union’s Minor Planet Center in Cambridge, Massachusetts.

Rubble pile

First the pair used a computer simulation to create hypothetical orbital paths around the sun that would have intersected with Earth at the time that the meteor hit. Then they searched a database of known asteroids for ones that could have produced rocks that follow those orbits . The closest match was with 2011 EO40.

Most asteroids aren’t solid rocks but rather rock clusters that have been gradually fragmenting for eons. “Most asteroids are rubble piles, very fragile,” says Carlos. So the brothers also simulated the disintegration of an object the size of 2011 EO40 and showed that it could fragment to produce a Chelyabinsk-size object that would impact with Earth at the correct time.

Future observations of 2011 EO40 could help confirm it as the Chelyabinsk parent. Analysing the light bouncing off it would let us match its composition to fragments of the meteorite collected in Russia. Sending a probe to bring back samples of the asteroid is the only way to be sure, but that is a hugely expensive mission that is unlikely to happen. “The cheap but not fully conclusive approach will have to suffice for the time being,” says Carlos.

Asteroid census

If 2011 EO40 really is Chelyabinsk’s parent, future observations should also help us predict if Chelyabinsk has any siblings still in orbit that might also pose a threat to Earth, says Carlos. “Having a precise census of this population can help us predict similar impacts in the future.”

Jorge Zuluaga of the University of Antioquia in Colombia, who traced the Chelyabinsk meteor to the Apollo asteroid family, cautions that EO40 2011 has yet to be confirmed as the parent. And even it is, he is not too worried about it spawning further impacts.

“I don’t think this particular asteroid is more hazardous than others in the MPC list,” he says. He also points out that the asteroid itself isn’t on a direct collision course with Earth, in any case.

Meanwhile, other researchers are working to piece together the orbit of the Chelyabinsk meteor by different methods. One recent study by Simon Proud of the University of Copenhagen, Denmark, unearthed satellite pictures that show what the meteor looked like from space as it streaked through our atmosphere (see image).

In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For the last twelve years, this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image: Marco Lorenzi).

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